Electromagnetic relay



lDec. 13,' 1927 D. D, MILLER ELECTROMAGNETI C RELAY Filed mmh 5.1. 192ePatented Dec. 13, 1927. l

UNITED STATES PATENT OFFICE..

DANIEL D. MILLER, F

Naw YORK, N. Y.,

ASSIGNR T0 BELL TELEPHONE LABORA- TGRIES, INCORPORATED, OE NEW YORK, N.Y., A CORPORATTON 0F NEW YORK.

ELECTROMAGNETIC RELAY.

Application led March 31, 1926. Serial No. 98,652. i

This invention relatcs'to electromagnetic relays, and more particularlyto improvements in the construction ot so 'called tlat type relays.

l The construction lot flat-type `relays is in general along the linesof the relay disclosed in Patent No. 1,121,897, issued December 22, 1914to E. B. Craft. The Graft relay is provided with a core -ot a flatsubstantially T-shaped piece of magnetic material, on the long shank ofwhich the magnetizing coil is wound. The shorter Shanks of this coreserve assupports Jfor a U-shaped armature ot -magneticV material, thebackwardly extending arms of which are secured to these Shanks by meansof a highly flexible spring, while the yokeportion of this U-shaped ar`mature is adapted to extend over the free end of; the long shank of thecore. In this manner the armature and the shorter shanks yot' the coreserve as return paths for the magnetic flux through the core portion.

It is an object ot this invention to improve the electrical operatingcharacteristics of relays of this general type by a construction tendingto decrease the magnetic reluctance 4and the magnetic leakage at theportions of the armature and core where they cooperate magnetically.That is, it is an object of this invention to provide a mechanical`structure whereby the reluctance of the path for the magnetic lines oftorce through the armature and core and the intervening air gap isgreatly reduced and whereby the leakage incidental to the passageotthese magnetic linesot force from one part to another is also reduced.

To attain this and other objects of the invention there is provided inaccordance with one feature thereof in 'place ot the usual U- shapedarmature Jfor flat type relays, an armature having a rectangular shapeof such comparative areas-and `cross sections across the portions wherethe armature cooperates magnetically standard commercial shape ot' therelay 'is maintained.

Another feature is the provision of a 5 construction in accordance withthis invention of dat type relays whereby the portion of the air gapbetween the core and arma ture, at the points nearest to the portions ofthe core and armature that it is intended should cooperate magnetically,and that are with the core that the magnetic.` reluctance ismateriallyreduced and yet the of necessity ineiiective during the operation of therelay due to relative position of the core to the armature in flat typerelays, is `so constructed that the amount of leakage across this `airgap is reduced.

Referring now to the drawing: Fig. l illustrates in perspective acomplete flat type relay embodying this invention?, Fig. 2 illustratesin perspective the shape, relative size and relation of the armature andcore of the relay shown in Fig. l and constructed in accordance withthis invention; Fig. 3 is a front view ot the relay shown in Figs. l and2 illustrating the relative shape and sizeof the magnetically operatingposition of the core and armature while Fig. fi is a front view of asimilar relay showing how the magnetically cooperating portions of thecore and'armature may be modified in regard to their shape.

In the drawing as a substantially Tehaped punching of magnetic materialcomprising a cross piece 2, a shank 8, ot a circular axial or othersuitable cross section, and flat enlarged ends or pole pieces l and 5.The armature l0 is a rectangularly shaped flat punching ot magneticmaterial having an enlarged pole piece l2 cooperating with the polepiece 5 and at its opposite end, a correspondingly enlarged cross piece-14 cooperating with pole piece 4. The cross piece 2 serves as a mountingplate Vtor the various piles of contact springs 28 and 29 tobecontrolled by the armature 10 and for mounting the relay itself tosuitable supports. The armature 10 is also secured to the cross piece 2by means of a resilient sheet steel plate 18 riveted to cross piece 2and having projections 19 and 20 riveted to the armature and acting as ahinge between the armature and the core. The spool heads 23 and 24 aremounted on the enlarged portions 5 andA 4, respectively, and the winding26 is carried on the core portion 3 between these two spool heads. Thetwo piles of contact springs 28 and 29 are mounted `as shown on oppositesides ot the coil 26 and are ar ranged to be controlled and operated bythe movements of the armature through the medium ot insulating studs,such as 30. The adjustment of the air gap between the pole piece 19. otthe armature and the pole piece 5 is regulated by means of a screw 32secured to the pole piece 5 and the nut 33 thereon which bears againstthe pole piece 1Q.

the core'piece l is shown Referring now particularly to the function ofa relay of this type constructed in accordance with this invention, itshould be noted that the armature forms a continuous path for themagnetic lines of 'torce from one air gap to t-he other; that theportions 19 and 5 and 14C and 4t are of comparatively elongated surfaceareas at the points where they cooperate magnetically rand that theseparts at these points are correspondingly reduced in a transversedirection to maintain the surface areas approximately the same as in thepresent flat type relays. There'torc, while the width of the air gapbetween these parts is less than in standard rela-ys ot this type, it isspread out or lengthened in a longitudinal direction to maintain thesame surface area. Consequently the magnetic reluctance of these airgaps to the magnetic lines of force seeking to pass between the armatureand core at these points is approXimately the same and may in fact,depending on the relative dimensions adopted. be considerably reduced.In other words, it the shanlrs 35 and 36 and 3 have been designed for acertain number ot magnetic lines of torce, the width across the air gapsand the area of the air gaps between 14 and 4 may be such that this airgap will citer considerably less reluctance to the magnetic lines offorce than has been possible in present designs of relays of this type.It is evident that due to the fact that the Shanks and 86 have to occupythe same transverse plane as the pole piece 5 and that the standardoutside dimensions ought to be maintained this construction ispreferable to wider pole pieces heretofore employed.

This construction also enables the armature and core to be so shapedthat a considerable reduction in the so called inellicient orineffective air gaps is produced. In other words due to the narrower andlonger pole piece 5 and armature cross piece 12 the portion of thearmature on either side of the portion 12 may bc so shaped that theyslant sharply away from the pole piece 5 and yet permit the shanks 35and 36 to be bent to occupy the same plane as the core as clearlyindicated in Fig. 3. By this construction the magnetic lines of torcetending to pass between the armature and core at these points aretherefore correspondingly reduced and the greater portion ott the'magnetic lines ot force will, consequently be directed to pass throughthe so called effect-ive air gap, that is, they must pass between thecore and armature at a point where they will perform the most work. Thusit will be seen that the leakage of magnetic lines ot force, that is7lines of torce that do not participate in the work of attracting thearmature to the core, is comparatively negligible and the generalefficiency ot the relay is therefore enhanced. Fig. 4 shows anotherapplication of this principle to further reduce the number of theineffective lines of torce passing between the core and armature. Thatis, the pole piece 5 is cut away at a steep angle at 39 so that the areaLt'or the passage of magnetic lines ot torce between the pole piece 5and port-ion 12 will be sharply dc- `fined.

`What is claimed is: l

1. An electromagnet comprising a core, a winding therefor, and a flatrectangularly shaped armature cooperatively associated with said core,the long sides of the armature being located in substantially the sameplane as the core and each of the short sides ot the armature being sobent as to straddle the corresponding end of the core to form aneffective air-gap and so bent that the ineii'ective air-gap incident tothis construction is lengthened to a maximum. y

2. An electromagnet comprising a core having flat ends and a middleportion, an energizing winding tor said core on the middle portionthereof7 a flat rectangularly shaped armature cooperatively associatedwith said core having its long sides located in substantially the saineplane as the middle portion of the core and having its short sidesstraddling respectively the flat ends of the core. one'short side hingedto a corresponding flat end of the core the other portion of the coreand the corresponding short side of the armature magneticallycooperating with each other, said last mentioned short side of thearmature being so shaped that the reluctance ot the eii'ective air-gapbetween these cooperating parts is small as compared with the reluctanceof the ineffective airgap incident to this construction.

3. An electromagnet comprising a core having tlat ends and anintermediate pore tion, an energizing winding for said core on theintermediate portion thereof, a Hat rectangularly shaped armaturecooperatively' associated with said core so that one short side of thearmature operates magnetically with one flat `end of the core, theYarmature being otherwise so shaped that the long sides thereof' arelocated in substantially the same plan-e as the flat ends of the core,the surface area of the magnetically cooperating parts being of arectangulaishape and so defined or arranged in relation to the otherportions of the armature and core that the majority of the magneticlines ot force will be directed to pass between these two rectangularsurfaces and confined sharply to the area thereof.

4. A flat type relay wherein the armature provides two parallel paths inthe magnet-ic circuit and wherein the armature face cor responding tothe core face is formed of a cross member bent about the core pole piececharacterized by the provision of a similar cross member for thearmature at the rear thereot` whereby the magnetic circuit is comis bentaboutJ said core pole piece being 10 pleted through an air gap betweenthe side nearer to the ends of said cross member than face of said rearcross member and the rear the center thereof, whereby the reluctance off face of said core piece, and a forward eX- the air-gap between thesides of said core 5 tension of the armature face corresponding polepiece and said armature is increased.

in general outline to said core face whereby In witness whereof, Ihereunto subscribe i5 the eective armature face area is enlarged my namethis 29 day of March A. D., 1926. so that the air-gap reluctance isreduced, the points at which said armature cross member DANIEL D.MILLER.

